'ED Visits for Cannabis Use a Harbinger of Anxiety Disorder'

 Patterns of cannabis use that lead patients to seek treatment in the emergency department (ED) may increase the risk of developing an anxiety disorder and worsen anxiety disorders in patients who already have them, according to new research.

In a population-based cohort study that included more than 12 million participants, about 24% of patients with an ED visit due to cannabis had an incident outpatient visit, ED visit, or hospitalization for an anxiety disorder in the subsequent 3 years. These patients were almost four times more likely to be diagnosed with an anxiety disorder than the general population. This risk was heightened in younger males with ED visits for cannabis use.

"There is a general notion that cannabis is relatively harmless and that it could even be a medicine to help with various conditions," lead author Daniel T. Myran, MD, MPH, an investigator at the Bruyère Research Institute and assistant professor of family medicine at the University of Ottawa, Ottawa, Canada, told Medscape Medical News. "But the signal we see in our study is that there is a group of individuals who may be quite susceptible to using cannabis and developing anxiety disorders from it, or who are using cannabis to alleviate their anxiety but only making it worse," Myran said.

Daniel T. Myran, MD, MPH

The findings were published on February 5 in The Lancet journal eClinicalMedicine 2024.

Cannabis and Anxiety

Cannabis use is increasing around the world, and cannabis is the third most commonly used drug after alcohol and nicotine. Meanwhile, the potency of cannabis has increased significantly.

Cannabis has fundamentally changed since the 1960s and '70s, said Myran. The concentration of tetrahydrocannabinol (THC), the psychoactive ingredient, in dried cannabis flower was 2% in the 1960s and '70s. "The stuff that's being sold in North America right now has 20%-30% THC, so it's 10 times stronger than what it was in the '60s and '70s," said Myran. "This boomer generation was using cannabis in the '60s, and they're trying it again now, and it's different."

The investigators used health administrative data to perform a population-based cohort study of all patients aged 10-105 years with no previous healthcare visits for anxiety disorders in Ontario between January 2008 and March 2019. They excluded all patients with a history of one or more healthcare visits for an anxiety disorder, as well as those who had one or more ED visits due to cannabis use in the previous 3 years.

They compared the risk for an incident healthcare visit for an anxiety disorder in the ED, hospital, or an outpatient setting among patients with a first visit to the ED for cannabis use and among the population overall.

The study cohort consisted of 12,099,144 patients without prior care for anxiety disorders in the ED or hospital. Of these patients, 34,822 (0.29%) had an incident ED visit due to cannabis use.

Compared with the general population, patients with an ED visit for cannabis use were younger (mean age, 27.6 years vs 44.9 years), more likely to be male (66.7% vs 49.1%), and more likely to live in the lowest-income quintile neighborhood (28.8% vs 19.3%).

They were also more likely to have had previous outpatient mental health visits (59.8% vs 26.0%), hospitalizations for noncannabis substance use (14.1% vs 0.8%), or a mental health condition other than anxiety (19.0% vs 1.0%) in the previous 3 years, compared with the general population.

Within 3 years of an incident ED visit due to cannabis use, 4294 patients (12.3%) had an incident ED visit or hospitalization for an anxiety disorder. This proportion represented a 3.7-fold (adjusted hazard ratio [aHR], 3.69) increased risk, relative to the general population (1.2%).

When the researchers refined their analysis to exclude patients with prior outpatient care for anxiety disorders, 23.6% of patients with an ED visit due to cannabis use had an incident outpatient visit, ED visit, or hospitalization for an anxiety disorder within 3 years, compared with 5.6% of individuals in the population (aHR, 3.88).

This increased risk was seen across all age and sex strata. Younger males with ED visits for cannabis use, however, had a greater risk, relative to the general population (aHR, 5.67), than younger women with cannabis use (aHR, 3.22).

Clinical, Policy Implications

Commenting on the findings for Medscape Medical News, Simon Sherry, PhD, professor of psychology and neuroscience at Dalhousie University in Halifax, Nova Scotia, Canada, said that the study joins other research suggesting that cannabis use predisposes the patient to anxiety symptoms. He was not involved with the research.

Simon Sherry, PhD

"These authors deserve credit for incrementally advancing our understanding of the connection between cannabis use and anxiety symptoms. Their innovative design and large sample allow us to better understand cannabis use as a risk for anxiety symptoms," Sherry said.

"People turn to cannabis to alleviate their anxiety. And indeed, cannabis may help reduce anxiety in the short term. However, cannabis does not seem to alleviate anxiety in the long term. Instead, cannabis makes anxiety worse over longer periods of time. In this way, cannabis is a seeming solution that eventually becomes a problem for cannabis users," Sherry concluded.

The study was funded by ICES and the Canadian Institutes for Health Research. Myran and Sherry reported no financial conflicts of interest.

https://www.medscape.com/viewarticle/ed-visits-cannabis-use-harbinger-anxiety-disorder-2024a10003a0